Scratcher for well bores



g- 1954 R. c. BAKER ET AL 2,685,931

SCRATCHER FOR WELL BORES Filed Feb. 7, 1950 5 Sheets-Sheet l INVENTORS.JPEUBEN C. BAKER,

ZZ/OMAS M BA 6AM Wad MM A77- TOE/V575 Aug. 10, 1954 R. c, BAKER ET AL2,685,931

SCRATCHER FOR WELL BORES Filed Feb. 7, 1950 5 Sheets-Sheet 2 JPEUBEN C.BAKER,

711044.45 M. EA GAIV,

INVENTORS.

,QrraEA/EYS Aug. 10, 1954 R. c. BAKER ET AL SCRATCHER FOR WELL BORES 3Sheets-Sheet Filed Feb. 7, 1950 iii, 5 I: iviNi It!!! iiihu W!!! 5155iii! 7!!! iii! PEI/BEN C. BAKER,

INVEN TORS.

Arraaws Y5 Patented Aug. 10, 1954 SCRATCHER FOR WELL BORES Reuben C.Baker, Coalinga, and Thomas M. Ragan, Downey, Calif., assignors to BakerOil Tools, Inc., Vernon, Calif., a corporation of California ApplicationFebruary 7, 1950, Serial No. 142,748

21 Claims. (Cl. 166173) The present invention relates to subsurface welltools, and more particularly to devices for scratching or scraping thewalls of open well bores, pipe disposed in well bores, and the like.

An object of the present invention is to provide improved scratcherdevices for more effectively removing mud cakes and other sheaths ofundesired materialsfrom the walls of bore holes, well conduits and thelike.

Another object of the invention is to provide wall scratchers havingoutwardly extending fingers that can engage and scrape a greater surfacearound the hole or pipe than in prior devices.

A further object of the invention is to provide wall scratchers that areof strong and sturdy construction, and which are economical tomanufacture and easy to assemble. 7

Yet another object of the invention is to provide wall scratchers thancan be assembled easily on a casing or similar string to be disposed ina well bore.

Still a further object of the invention is to provide wall scratchers inwhich each spring scratching element supports and supplements the other,thereby providing a greater spring force for scratcher purposes than theindividual scratching elements can f urnish.

Another object of the invention is to provide wall scratcher devicespossessing zero or light wall scratching force when the devices aremoved through the well bore in one direction, as downwardly, and amaximum wall scratcher force when the devices are moved in the oppositedirection, as upwardly.

Still another object of the invention is to provide wall scratchers thatnot only are effective in scratching the wall of the hole, but which arealso capable of centering the well conduit,,on which one or more of thescratchers are mounted, in the hole.

This invention possesses many other advantages, and has other objectswhich may be made more clearly apparent from a consideration of severalforms in which it may be embodied. Such forms are shown in the drawingsaccompanying and forming part of the present speci- 'fication. Theseforms will now be described in detail, illustrating the generalprinciples of the invention; but it is to be understood that suchdetailed description is not to be taken in a limiting sense, since thescope of the inventionis best defined by the appended claims.

Referring to the drawings:

Figure 1 is a side elevation of one form of wall scratcher mounted on acas ng Section;

Fig. 2 is a cross-section taken along the line 2-2 on Fig. 1;

Fig. 3 is a somewhat diagrammatic view of a Wall scratcher mounted on acasing string during lowering of the latter in a well bore;

Fig. 4 is a view similar to Fig. 3, disclosing elevation of the casingstring and scratcher in a the Well bore;

Fig. 5 is a fragmentary cross-section, on an enlarged scale, throughpart of the scratcher device disclosed in Figs. 1 and 2;

Fig. 6 is a section taken along the line- 6-E on Fig. 5;

Fig. 7 is a fragmentary interior elevation taken as indicated by theline '!'I on Fig. 6;

Fig. 8 is a view similar to Fig. 6 of a modified form of wall scratcher;

Fig. 9 is a view similar to Fig. 5 of still another form of wallscratcher;

Fig. 10 is a plan view of one of the scratcher elements employed in theembodiment of invention disclosed in Figs. 1 to 7, inclusive;

Fig. 11 is a side elevation of the scrateher element shown in Fig. 10;

Fig. 12 is a fragmentary longitudinal section through a hinge elementused in the scratcher devices;

Fig. 13 is a view similar to Fig. 6 of another embodiment of wallscratcher.

As disclosed in the drawings, a wall scratcher A is mounted on a casingor well conduit section B for the purpose of removing the mud cake froma portion of the well bore C in which the casing string is to bedisposed, and also to center the casing string in the Well bore. It isde-- sired to remove the mud cake or sheath D from a particular portionof the well bore, in order to insure a proper bond between the formationwall and cement slurry, or other cementitious ma terial, pumped down thecasing string for up Ward passage through the annulus around the latter.However, it is preferred not to disturb the mud cake to any substantialextent, except along that portion of the formation wall at which cementis to be disposed. For that reason, the Wall scratcher A should scratchthe mud cake D lightly, if at all, during descent of the casing stringthrough the well bore. However, the scratching effectiveness should beat a maximum during the upward movement of the casing scratcher in thewell bore.

The wall scratcher A could be firmly secured to the casing string, butit is preferred to provide for its slidable mounting thereon. Thus, theWall scratcher includes a collar or sleeve it slidable on a casingsection B, and adapted to engages stop elements ll, [2, such as ring members, welded to the casing section on opposite sides of the scratcher A.These stop elements I I, H may be disposed a few feet apart. Duringdownward movement of the casing string in the well bore, the upper stopelementl I will engage the collar 43 and force the scratcher devicedownwardly through the well casing. However, during upward movement ofthe casing string B to a slight extent, such as occurs'in lifting thecasing string out of the rotary table slips at the top of the well bore,the scratcher device need not move in an upward direction, inasmuch asthe lower stop element" i'zwillnot en gage the lower end of the collarIt during such slight upward movements of-the casing string. Greaterupward movements, however, will. engage the lower ring with-the collarand'mcve' the scratcher device upwardly with the casing string.

The collar has an outwardly directed bead portion it formed in itprovided with a rowof circumferentially spaced apertures or holes Hi,that are preferably equi-distantf-rom one another. A retainer fulcrum orassembly ring 15, which may be made of steel wire, is disposed Withinthe head 13 and extends substantially entirely around the interior ofthe collar Ill. Scratcher elements it are mounted on-"the ring Ii-whichserves as af-ulcrum'about which the elements l'fi'inay-pivot.

Each scratcher element it includes a heel or base portion i'l extendingalong the ring 15 and merging into coil portions 8 at its opposite ends.Each coil portion iflmayconsist of one or a plurality of turns,asdesired-and is disposed opposite one or" the bead apertures i l onopposite sides of the heel or base ll. From each c'oilpo'rtion H3, acomparatively long-wire finger til or 28 ex tends through the apertureor hole it. Thus, one elongate finger I9 extends through onehole it atone side of the" base l1,andanother wire finger 2!! extends through anadjacent'h'ole'i at the other side of the base.

It is evident that the "coils l8 serve'to mount "each'scratcherelementon the ring 5. The parts are so arran ed that the heel portion i"! ofthe element it is disposed above the ring I 5 and will engage the upperinner'portion of the head it (see Fig. 6) to limit the extent of outwardswinging of the fingers i9, about the ring t5. When 'the heel portion Il engages thebea'd l3, the fingers i9, 26 are preferably inclined in anup ward and outwarddirectionas disclosed most clearly in Fig. 6.Thespring fingers 19, 2'0 can swing in a downward direction about'thering [5 to a still further extentf'but such action is resisted by thecoil portions it, which are wound or unwound (depending upon "thedirection of their coiling) to provide the spring force resistingoutward swinging of thefingers. During such winding or unwinding of'thecoils I'8,the'heel portions il engagelthe inner wall of the bead l3, andoffer resistance to the winding action of the coils with respect to theretainer ring i5.

Upward and inward movement of the spring fingers 5'9, 29 about theretainer ring cantake place to an extent limited by engagement of theinnerportions 2! of the fingers with the sides of the collar aperturesl4. Such engagement will insure the upward and outward inclination ofthe fingers I9, 2 tea minimum extent, which may be sufficient tobearagainst the wall of the well here C relatively lightly. Any furtherinward force of the wallof the well core on the, springs 19, as willbend them inwardly about the wall defining the aperture 14.

The scratcher elements it are mounted on the ring with their fingerportions is, as extending through the apertures i4 and projectingoutwardly beyond the collar iii to a substantial extent. The assembledscratcher device A is mounted on a casing section B,'-with the upper andlower stop elements 5 Llz'weldecl to the latter appropriate distanceapart on opposite sides of the scratcher device. Th casing string-islowered through the well here, the upper stop element H engaging thecollar i6 moving the'scratcher downwardly through the well casing.During-such downward movement, the spring fingers While can merely ridealong the mud cake D or wall of the well here C, exerting alight orzeroforce against the casing wall. The extent of inward movement of thefingers i9, 29 is determined by engagement of their inner portions 2iwith the upper walls of the apertures M. As indicated above,small'elevation of thesesing string will not move the 'scratcher in' anupward direction, inasmuch as the lower stop'el'ement 12 will notbrought into'engagement with the lower end i thecollar H3.

-When the portion in the ell loore C has been reached in which thescratching operation isto take place, the casing string is elevated theproper distance, the lower stop element 2?. engaging'the collar It 'andmoving'it-in an upward direction. Duringsuch upward movement, the endsof-t'ne fingers 19, engage the mud cake D, such engagement causing thefingers to tendto swing downwardly and outwardly, shifting the fingersto a position in which they penetra-tethe mud cake and possiblylie-"riding them downwardly through the transverse plane of the bead asindicated. in the-lowermost broken line position. Shown in Fig. 6.Continued upward movement causes the fingers -19, "25 to scratch alongthe mud cake D, breaking it intorelativeiy small pieces, which can beflushed from the well core by the circulating fluid pumped downwardlythrough the well-casing, Such downward and outward swinging of fingersi3, is resisted :by the engagement of the heels ii of the scratcherelements with the collar l3, and by the winding or unwinding of thecoils l8 about the retainer ring i 5.

Most of the spring force resisting pivoting or" the fingers it, aboutthe retainer ring it is supplied by the spring coils it, a small amountbeing furnished by the bending of the fingers themselves.

The casing string B may be reciprocated the 'desirednumber of times toinsure removal of the mud cake from the wall or" the well here alongthedesired'length. The removal of the mud cake is evidenced by the mudparticles appearing in' the circulating fluid. as it leaves the top ofthe well bore.

'In' the scratcher assembly disclosed in Figs. 1 to 7, inclusive, eachscratcher element is is mounts on the ring 65, "with its fingers i9, 29passing through adjacent holes id, M on opposite sides of the heelportion H" or" he element. The next adjacent scrateher' element It ismounted on the retainer or assembly l5, with one of its fingers 59extending through the same hole it a-s-a finger 29 of an adjoiningelement. That is, the scratcher elements are so arranged that twofingers i9, '29 of different elements pass through each bead hole oraperture it, one finger from one element and another finger from theadjacent element. Because of this arrangement, a gr ater number ofscratcher elements it can be disposed around the collar I0, multiplyingthe number of fingers I9, 20 available for scratching purposes on theformation wall C or on the wall of a pipe (when the device is used forscratching or scraping the wall of the pipe).

In the arrangement disclosed in Figs. 1 to 7, the scratcher elements Itare caused to support or supplement one another. This is accomplished bybending the major portion 25 or 25 ofeach finger with respect to itsinner portion 21 or 28 adjacent the collar bead I3. As disclosed in thedrawings, the fingers I9, 28 of each element are bent away from oneanother so as to overlie one or more fingers of adjacent elements. Thus,an inner portion 26a of a finger 2:! of one scratcher element is causedto overlie and will cross the inner portion 25a of an adjacent finger I9 of another element. In addition, the same finger 29 of a scratcherelement will overlie and cross an intermediate portion 25b of a fingeris of a third scratcher element. Because of this engagement of ascratcher finger 21' with one or a plurality of fingers I9 of otherscratcher elements, the latter two support the first-mentioned finger2B. As a result, during upward movement of the casing string to scratchthe mud cake D from the wall of the formation, the first finger it willengage the wall of the hole and its downward pivoting about the retainerring I5 will be resisted not only by its own coil spring portion I8, butalso by engaging and tending to move downwardly the fingers I 9 of theother two scratcher elements, the downward movement of these fingersbeing resisted by their respective coil spring portions :6.

It is to be noted that one finger 26 of each scratcher element It issupported by two fingers I9 on two other scratcher elements and that theother finger I9 of the first-mentioned scratcher element It furnishesthe supplemental force and resistance for two other fingers 28 of twoother scratcher elements.

The crossing arrangement of fingers 29, It not only supplements thescratcher force available for removing the mud cake from the formationWall, but also insures engagement of all of the fingers with the Wall ofthe hole. As one finger 29'is swung downwardly and outwardly about theretainer ring I5, it moves the overlapped fingers i9 downwardly; so asto insure their engagement with and digging into the mud cake I) andformation wall C. V The scratcher device can be easily assembled, eachspring element I6 being placed within the collar and its oppositefingers I 8, is disposed through a pair of bead apertures or holes I4,with the fingers appropriately overlapping one another. The wireretainer ring 15 can then be threaded through all of the coils I8, andthe ring itself appropriately secured, as by welding, to the bead I3 toinsure that it will remain in place.

In order to obtain a greater number of scratch ing elements It foraction upon the mud cake and to insure that a much greater wall surfacewill be scratched, a plurality of sets 3B, 3! of scratcher elements maybe mounted on the collar It. As shown in Fig. 1, an upper and a lowerbead 53, I30. is formed in the collar, the apertures I ia in the lowerbead I34: being offset with respect to the apertures I 4 in the upperbead I3. The spring elements It extend through the upper and lower beadsI3, I 3a and are assembled in essentially the same manner, the lowerscratcher elements I6 being offset slightly with respect to the upperscratcher elements, in order that the ends of the v 6 fingers I9, 20 ofthe lower set 3! will engage different circumferential portions of theformation wall than the ends of the fingers of the upper set 30. I

The action of the multiple set arrangement of scratcher elementsdisclosed in Fig. l is essentially the same as the single set, themultiple set ofiering assurance of effective removal of the mud cakefrom the desired region where the cement bond is to be achieved with theformation wall.

In order to facilitate mounting of the scratcher device on the casingsection, it can be made of split or hinged construction. As disclosed inthe drawings, the collar or sleeve 19 is made in two parts 59a, Iiib,which is also true of the retainer or fulcrum ring I501, I522. Eachretainer or fulcrum ring portion is suitably secured, as by welding, tothe bead portion 13 of the collar, each ring section i504, I52)terminating at the ends of the collar section Illa, Ifib. The collarsections Illa, Illb are hinged together at one side of the device bywelding or otherwise securing opposed hinge plates 35at the ends ofopposite sections, and by inserting a suitable hinge pin 36 through theinterleaved hinge knuckles 3's". Preferably, a hinge 35, 35, 3? isplaced on the upper and lower portions of the collar sections laid, it?)above and below the collar heads is (see Fig. 1). Such pair of hingeshave a common axis about which they may pivot.

On the opposite side of the collar a like pair of hinges 38 is provided.However, the hinge pins 36 are omitted from such hinges, in order thatthe collar Ill may be opened, swinging its half sections Ifia, lob aboutthe axis of the other hinge pins 36, the device then being movedtransversely and placed around a casing section between the stopelements I I, I 2 that may already be provided thereon. As a matter offact, one of the stop elements may be constituted by the usual coupling(not shown) that may be employed to connect adjacent casing sectionstogether. The collar is then closed about the casing section and pins 39placed through the knuckle portions 3'1 of the opposite hinge parts. Asdisclosed in the drawings, such pin elements may take the form of drivescrew nails which are driven through the interleaved knuckles 3?, thehelical threads or ribs 3 0 on the shank portions of the nails formingor cutting their own threads in the interior of the knuckles 3?, andsecurely fastening the two halves of each hinge it together. The drivescrew nails form a rapid and eifective mannor of closing the scratcherdevice A around the casing and of holding them properly mounted inposition thereon, inasmuch as pivoting action of the hinges 35, (it, 37is no longer necessary once the device has been assembled on the casingsection.

In the form of invention disclosed in Figs. 1 to 7, inclusive, upwardmovement of the spring fingers I9, 29 is limited by engagement of theirinner portions 21, 28 with the side walls of the apertures Id. In theform disclosed in Fig. 8, the spring elements 55a are inverted withrespect to the positions they occupied in the other form of theinvention, with the heel portions Ila disposed downwardly and exteriorlyof the head 53. With this arrangement, the heel portion lla will engagethe lower external surface of the head i3 to limit the extent of freedownward swinging of the fingers I9a or 2%. However, the inverting ofthe elements allows them to swing upwardly about the retainer ring it toa greater extent before the finger 19a or 20a will engage the sides ofthe aperture Id, thefingers, in fact, being able to be collapsed to acomparatively small effective diameter and completely out of engagementwith the wall of the well bore. As a result, during downward movement ofthe casing string in the well bore, the fingers tea, tea will offer noscratching force upon the formation wall or mud cake D, but upon upwardmovement of the casing string with the lower stop element l2 inengagement with the collar id, the outer ends of the spring elementswill engage the formation wall or mud cake and perform a scratchingaction in the same manner as in the other form of the invention.

In the form disclosed in Fig. 9, the fingers Isl), 20b of each scratoherelement do not overlap one another, but extend substantially radiallyoutward; so as to engage the mud cake D and scratch it from theformation wall, without the spring force of one element ltb beingsupplemented by the resisting spring force of adjacent elements lfib.

The scratcher element illustrated in Fi 13 has its end portions-50turned upwardly at an angle to the main portions of the fingers IS, 29.With this arrangement, the terminals of the portions 56 can functionlike claws or teeth in di ging away the mud cake D during upward movement of the scratcher device, as is evident from the broken lineposition shown in Fig. 13.

It is apparent that scratcher elements have been devised which caneffectively remove the mud cake and other sheaths from the walls of boreholes and well conduits, and in which a maximum scratcher force isavailable for resisting deflection of the spring fingers and forinsuring removal of the toughest mud sheaths from the wall of the wellbore. The provision of a plurality of rows of scratcher elements onsetwith respect to each other insures the coverage of a greatercircumferential extent by the scratcher fingers along the wall of thewell bore, and the removal of all of the mud cake from the desired.region in the hole. Each scratcher finger may operate individually ormay have its scratching action supplemented by the resisting force ofadjacent spring fingers, which increases the strength and sturdiness oi"the device considerably. During downward movement of the casing stringin the well casing, a small or non-existent scratching force is appliedagainst the wall of the well bore, but during upward movement, asubstantial and great force for scratching the hole wall is present. Thewall scratchers can be readily assembled and can be easily mounted on acasing or similar conduit string. In addition totheir scratching action,they serve to center the conduit string in the well bore, in order toinsure a more uniform deposition of cement slurry around the casingstring and thereby prevent channeling.

The inventors claim:

1. In a wall scratcher: a collar having a pin rality of aperturesextending through its side wall and adapted to'be mounted on exterior ofa well conduit; a plurality of spring elements disposed adjacent eachother substantially in a common plane and extending laterally outwardthrough said collar apertures, each element havinga coil portiondisposed in the in'erior of said collar; and means inside of said collarextending through said coil portions for. mounting. said elements onsaid collar.

2. In a wall scratcher: a. collar having a plurality of aperturesextending through its side wall and adapted to be mounted on theexterior of a well conduit; a plurality of sping elements disposedadjacent each other substantially in a common plane and arranged aroundsaid collar; each element including an outwardly projecting fingerextending laterally outward through an aperture and merging into aspring coil disposed inside of said collar, said coil merging into aheel contactable with said collar; and means in the interior of saidcollar extending through said coils for mounting said elements on saidcollar.

8. In a wall scratcher: a tubular collar adapted to be mounted on theexterior of a well conduit and having an inner generally cylindricalwall, said collar having a plurality of apertures extending through saidwall; a plurality of spring elements disposed adjacent each othersubstantially a common plane and arranged around said collar; eachelement including an outwardly projecting finger extending laterallyoutward through an aperture and merging into a spring coil disposed inthe interior of said collar, said coil merging into a heel oontactahlewith the inner wall of said collar; and means inside of and secured tosaid collar extending through said coils for mounting said elements onsaid collar.

i. In a wall scratcher: a collar having an apertured, outwardly directedcircumferential head formed therein; a plurality of spring elementsarranged around said collar, each element including a finger extendingthrough a bead aperture and a spring coil disposed in the interior ofsaid collar and within said head; and means within said head extendingthrough said coils for mounting said elements on said collar.

5. In a wall scratcher: a collar havingan apertured, outwardly directedcircumferential bead formed therein; a plurality of spring elementsarranged around said. collar, each element including a finger extendingthrough a bead aperture, a spring coil disposed in the interior of saidcollar and within said bead, and a heel secured to said coil andcontactable with said collar; and means within said head extendingthrough said coils for mounting said elements on said collar.

6. In a wall scratcher: a tubular collar adapted to be mounted on theexterior of a well conduit and having a plurality of apertures extendingthrough its side wall; a plurality of spring elements disposed adjacenteach other substantially in a comrnonplane and arranged around andextending laterally through said collar apertures; each elementincluding a pair of outward ly projecting fingers separate from eachother, spring coils in the interior of said collar and secured to saidpair of fingers, and a heel secured to said coils and contactablewithsaid collar; and

cans extending through said coils for mounting said elements on saidcollar.

7. In a wall scratcher: a tubular collar adapted to be mounted on theexterior of a well conduit and having an inner generally cylindricalwall, said collar having a plurality of apertures extending through itsside wall; a plurality spring elements arranged around and extendinglaterally through said collar. apertures; each element including a pairof outwardly projecting separate fingers, spring coils in the interiorof said collar and secured to said pair of fingers and disposed withinsaid collar, andaheel secured to said coil and contactable with theinner wall or said collar; and means withinandsecured to said collarextending through said coils for mounting said elements on said. collar.

8. In a wall scratcher: a collar having an apertured, outwardly directedcircumferential bead formed therein; a plurality of spring elementsarranged around said collar, each element including a pair of outwardlyprojecting fingers extending through said bead apertures, spring coilssecured to said pair of fingers and disposed in the interior of saidcollar and within said bead, and a heel secured to said coils andcontactable with the inner wall of said collar; and means within saidbead extending through said coils for mounting said elements on saidcollar.

9. In a wall scratcher: a collar having a plurality of aperturesextending through its side wall; a plurality of spring elements disposedcircumierentially around said collar substantially in a common plane andextending laterally through said collar apertures, said elements havingfingers separate from each other and overlapping and contacting fingersof adjacent elements in a direction circumferentially around saidcollar, said fingers extending laterally outward of said collar to asubstantial extent; and means mounting said elements on said collar.

10. In a wall scratcher: a collar having a plurality of aperturesextending through its side wall; a plurality of spring elements arrangedcircumferentially around and extending laterally through said collarapertures; each element including a lateral and outwardly projectingfinger merging into a spring coil disposed in the interior of saidcollar, said coil merging into a heel contactable with said collarythefinger of one element overlapping and contacting finger of an adjacentelement in a direction circumferentially around said collar; and meanswithin said collar extending through said coils for mounting saidelements on said collar.

11. In a wall scratcher: a collar having a plurality of aperturesextending through its side wall; ,a plurality of spring elementsarranged circumferentially around and extending laterally through saidcollar; each element including a pair of lateral outwardly projectingfingers, spring coils secured to said pair of fingers and disposed inthe interior of said collar, and a heel secured to said coils andcontactable with said collar; a finger of each element overlapping andcontact- .ing one or more fingers of other elements in a directioncircuinferentially around said collar; and means extending through saidcoils for mounting said elements on said collar.

12. In a wall scratcher: a collar having an apertured, outwardlydirected circumferential bead formed therein; a plurality of springelements arranged around said collar, each element including a pair ofoutwardly projecting fingers extending through adjacent bead apertures,spring coils secured to said pair or fingers, and a heel secured to saidcoils and contactable with said collar between the apertures throughwhich the fingers project; the fingers of each element diverging in anoutward direction with respect to each other so as to overlap andcontact the fingers of adjacent spring elements; and means within saidbead extending through said coils for mounting said elements on saidcollar.

13. In a scratcher: a collar having an apertured, outwardly directedcircumferential bead formed therein, said collar comprising a pluralityof sections longitudinally spaced hinge means on opposite sides of saidhead securing said sections together at one side of said collar;longitudinally spaced detachable means on opposite sides of said beadsecuring said sections together at the opposite side of said collar; aplurality of spring elements arranged around said collar, each elementincluding a finger extending through a bead aperture anda spring coildisposed within said bear; and an annular member secured to said collarandextending through said coils to mount said elements on said collar,said annular member comprising a plurality of sections conforming to thecollar sections.

14. In a wall scratcher: a collar having an apertured, outwardlydirected circumferential bead formed therein; a plurality of springelements arranged around said collar, each element including a pair ofoutwardly projecting fingers extending through different bead apertures,spring coils secured to said pair of fingers, and a heel secured to saidcoils and contactable with said collar between the apertures throughwhich the fingers project; the fingers of each element diverging in anoutward direction with respect to each other so as to overlap andcontact the fingers of adjacent spring elements in a directioncircumferentially of said collar.

15. In a wall scratcher: a collar having an apertured, outwardlydirected circumferential bead formed therein; a plurality of springele-. ments arranged around said collar, each element including a pairof outwardly projecting fingers extending through difierent beadapertures, spring coils disposed within said bead and secured to saidpair of fingers, and a heel secured to said coils and contactable withsaid collar between the apertures through which the fingers project, thefingers of each element diverging in an outward direction with respectto each other so as to overlap and contact the fingers of adjacentspring elements in a direction circumferentially of said collar.

16. In a Wall scratcher: a collar having a plurality of aperturesdisposed circumferentially therearound; a plurality of spring elementsarranged around said collar, each element including a pair of outwardlyprojecting fingers extending through different collar apertures, springcoils on the inside of said collar and secured to said pair of fingers,and a, heel secured to said coils and contactable with said collarbetween the apertures through which the fingers project; the fingers oreach element diverging in an outward direction with respect to eachother so as to overlap and contact the fingers of adjacent springelements in a direction circumferentially of said collar.

17. In a wall scratcher: a member having an apertured, outwardlydirected bead formed therein; a plurality of spring elements disposedalong said bead, each element including a pair of outwardly projectingfingers extending through different bead apertures, spring coilsdisposed within said bead and secured to said pair of fingers, the axesof said coils extending generally along the length of said bead, and aheel secured to said coils and contactable with said member between theapertures through which the fingers project; the fingers of each elementdiverging in an outward direction with respect to each other so as tooverlap and contact the fingers of adjacent spring elements.

18. In a wall scratcher: a member havin an apertured, outwardly directedbead formed therein; a plurality of spring elements disposed along saidbead, each element including a pair of outwardly projecting fingersextending through different bead apertures, spring coils disposed withinsaid bead and secured to said pair of fingers, the axes of said coilsextending generally alon the 11 length of said bead, and a heel securedto said coils and contactable with saidmember between the aperturesthrough which the fingers project.

19. In a wall scratcher: a member having an apertured and outwardlydirected bead formed therein; a plurality of spring elements disposedalong said head, each element including an outwardly projecting fingerextending through a bead aperture, a sprin coil disposed within saidbead and secured to said fingers, and a heel secured to said coil andcontac'table with said member; the axes of said coils extendinggenerally along the length of said bead.

20. In a wall scratcher: a member having an internal groove therein anda plurality of spaced apertures; a plurality of spring elements disposedalon said groove, each element including a pair of outwardly projectingfingers extending through different apertures, spring coils disposedwithin said groove and secured to said pair of fingers, and a heelsecured directly to said coils and contactable with said member; theaxes of the coils of said spring elements extending generally lengthwiseof said groove.

21. In a wall scratcher: a collar having an apertured, outwardlydirected bead formed therein; a plurality of spring elements arrangedcircumferentially around said collar, each element including a pair oflateral and outwardly projectin fingers extending through difierent beadapertures and also including an intermediate portion disposed withinsaid bead; said apertures being of a greater area thanthe area of saidfingers to permit rotation of said spring elements in said head;meansadapted to abut each spring element to prevent rotation of saidelement on the collar beyond a predetermined point, said meanscomprising a portion of the collar adjacent said aperture which isengaged by a portion of each spring element, the fingers of each elementdiverging in an outward direction with respect to each other so as tooverlap and contact the fingers of adjacent elements in a directioncircumferentially around said collar; and means engageable with saidelements to prevent substantial movement of said elements inwardly ofsaid collar.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 181,416 Davis Aug. 22, 1876 574,972 Wiens Jan. 12, 18971,040,118 Batt Oct, 1, 1912 1,371,425 Jones Mar. 15, 1921 1,557,166 HornOct. 13, 1925 2,298,985 Still et al Oct. 13, 1942 2,315,069 McKean et alMar. 30, 1943 ,36 ,198 Gibson Nov. 7, 1944 2,412,876 Edwards Dec. 17,1946 2,421,434 Reistle et a1 June 3, 1947 2,427,632 Stephens Sept.16,1947 2,506,405

Wright May 2, 1950

